Natural MoS2 is an indirect gap semiconductor (1.2 eV) but becomes highly luminescent in the monolayer from at 1.9 eV (quasi-particle / optical band gap). Natural crystals are lower grade compared to our synthetic MoS2 crystals in terms of purity, defect concentration, and crystallinity. These natural source MoS2 crystals come in different sizes ranging from small, medium, and to large MoS2. In their untouched form, they contain large amount of impurities such as Fe, O, Cr, Ni, C, Se, P, and Si. These natural source crystals undergo a number of cleaning process to eliminate these impurities from the edges, surfaces, macroscale defect sites, as well as macroscopic cracks within the specimen. During this process, approximately 90% of the crystal is eliminated to bring you only the clean pieces for research use.
Crystal size (minimum) 10x10 mm
Photoluminescence spectrum from monolayer MoS2 sheets exfoliated from MoS2 crystals
Raman spectrum from synthetic MoS2 crystals
XRD data collected from synthetic MoS2 crystalsCharacterizationRaman spectroscopy: Raman spectroscopy is data is taken on every piece. Typically, flakes show two prominent Raman peaks at 383cm-1 (E2g- in plane-) and 409cm-1 (A1g out-of-plane) and the FWHM (full-width-at-half-maximum) is less than 5cm-1 showing highly crystalline nature. Photoluminescence (PL): In the bulk form (2H-MoS2), molybdenum disulfide possess indirect band-gap at 1.3eV. Therefore, PL measurements cannot probe the band-gap directly. However, after illuminating with high laser intensity (hot photoluminescence) PL shows peak at 1.3eV.
Publications from this product
Summary: Publications from Cornell, Washington, MIT, Berkeley, Stanford, and Princeton teams at top journals like Nature, Nature Materials, Nature Communications, Nano Letters, and Advanced Materials
Zefei Wu, Shuigang Xu, Huanhuan Lu, Armin Khamoshi, Gui-Bin Liu, Tianyi Han, Yingying Wu, Jiangxiazi Lin, Gen Long, Yuheng He, Yuan Cai, Yugui Yao, Fan Zhang, and Ning Wang. "Even–odd layer-dependent magnetotransport of high-mobility Q-valley electrons in transition metal disulfides." Nature communications 7, 12955 (2016).
Zefei Wu, Benjamin T. Zhou, Xiangbin Cai, Patrick Cheung, Gui-Bin Liu, Meizhen Huang, Jiangxiazi Lin, Tianyi Han, Liheng An, Yuanwei Wang, Shuigang Xu, Gen Long, Chun Cheng, Kam Tuen Law, Fan Zhang and Ning Wang "Intrinsic valley Hall transport in atomically thin MoS2." Nature communications 10, 611 (2019).
C. Robert, "Optical spectroscopy of excited exciton states in MoS2 monolayers in van der Waals heterostructures" Phys. Rev. Materials 2, 011001(R) (2018)
Weigao Xu et al., "Correlated fluorescence blinking in two-dimensional semiconductor heterostructures", Nature 541, 62-67 (2017), link to article:
Manish Chhowalla team "Phase-engineered low-resistance contacts for ultrathin MoS2 transistors" Nature Materials DOI: 10.1038/NMAT4080
X. Chen "Probing the electron states and metal-insulator transition mechanisms in molybdenum disulphide vertical heterostructures" Nature Communications 6, Article number: 6088 (2015) doi:10.1038/ncomms7088
Measurement of the optical dielectric function of monolayer transition-metal dichalcogenides: MoS2, MoSe2, WS2, and WSe2, Yilei Li, Alexey Chernikov, Xian Zhang, Albert Rigosi, Heather M. Hill, Arend M. van der Zande, Daniel A. Chenet, En-Min Shih, James Hone, and Tony F. Heinz; Phys. Rev. B 90, 205422 (2014)
H. Wang et.al. "Ultrafast response of monolayer molybdenum disulfide photodetector" Nature Communications 6, Article number: 8831 (2015)
Y. Jin "A Van Der Waals Homojunction: Ideal p–n Diode Behavior in MoSe2" Advanced Materials 27, 5534–5540 (2015)
Tongay et. al. "Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged, and free excitons" Scientific Reports 3, Article number: 2657 (2013)
X Li et al. "Determining layer number of twodimensional flakes of transition-metal dichalcogenides by the Raman intensity from substrates" Nanotechnology 27 (2016) 145704
Tongay et.al. Thermally Driven Crossover from Indirect toward Direct Bandgap in 2D Semiconductors: MoSe2 versus MoS2; Nano Letters, 2012, 12 (11), pp 5576–5580
Manish Chhowalla, "Two-dimensional semiconductors for transistors" Nature Reviews Materials 1, Article number: 16052 (2016) doi:10.1038/natrevmats.2016.52
D. Wolverson et.al. "Raman Spectra of Monolayer, Few-Layer, and Bulk ReSe2: An Anisotropic Layered Semiconductor" ACS Nano, 2014, 8 (11), pp 11154–11164
M. Yankowitz et. al. "Intrinsic Disorder in Graphene on Transition Metal Dichalcogenide Heterostructures" Nano Letters, 2015, 15 (3), pp 1925–1929
H. C. Diaz et.al. "Molecular beam epitaxy of the van der Waals heterostructure MoTe2 on MoS2: phase, thermal, and chemical stability" 2D Materials, Volume 2, Number 4 (2015)
A. Gul et.al. "Theoretical and experimental investigation of conjugation of 1,6-hexanedithiol on MoS2" Materials Research Express, 5 (3), 036415 (2018)